Implementing Education for Sustainable Development in Primary Schools: Teacher Perceptions, Practices, and Regional Challenges in an Island Context

(1) Background: Education serves as a catalyst for social transformation toward sustainability, yet limited empirical evidence exists regarding primary education’s contribution to regional sustainable development, particularly in island contexts facing unique environmental and economic pressures. This study examined primary education teachers’ perceptions, practices, and challenges in implementing Education for Sustainable Development (ESD) in Zakynthos, Greece. (2) Methods: A triangulated quantitative approach surveyed a representative sample of 105 primary education teachers from the Zakynthos Primary Education Directorate using a 28-item structured questionnaire assessing ESD knowledge, teaching practices, barriers, and improvement strategies. Teacher questionnaire data were triangulated with KEPEA (Center for Environmental Education and Sustainability) program documentation (103 programs, 2020–2025) and school implementation records from 75 participating schools. Data were analyzed using descriptive statistics, Mann–Whitney U tests, Kruskal–Wallis tests, and Spearman correlations. (3) Results: Most teachers (65.7%) reported adequate knowledge of sustainable development concepts, with 75.3% incorporating ESD into teaching practice often or very often. Triangulation revealed convergent findings: environmental sustainability dominated teacher perceptions (67.3%) and KEPEA programming (78.4%), while economic sustainability received limited attention (18.1%). Female teachers demonstrated significantly higher ESD knowledge (U = 892.5, p < 0.05, r = 0.34). The majority (98.1%) considered ESD integration important, yet only 48.5% felt adequately prepared to teach sustainability topics. A notable attitude-action gap emerged: while 86.6% valued community partnerships, only 47.6% engaged frequently, and KEPEA documented 33.7% of formal collaborations. Primary barriers included insufficient curriculum time (61.9%) and limited resources (51.4%). Teachers identified training programs (71.4%) and access to educational materials (71.4%) as priority interventions. (4) Conclusions: Primary education teachers in Zakynthos demonstrate strong commitment to ESD but face structural barriers limiting implementation effectiveness. The environmental-economic imbalance suggests a need for professional development, integrating economic sustainability concepts through place-based approaches relevant to the island’s tourism-dependent economy. The attitude-action gap in partnerships indicates structural rather than attitudinal barriers requiring policy intervention. Findings support targeted teacher training, curriculum reform, and strengthened school-community collaboration to enhance ESD’s contribution to regional sustainable development.